In two studies, tobacco users were tested with a commercially available smokeless tobacco product (i.e., pouches of snuff), and with a smokeless cigarette through which air is sucked to inhale vaporized nicotine. Standardized methods of abuse liability assessment were used. The smokeless tobacco study consisted of two phases. The first evaluated the effects of dose and the possibility that rate of expectoration would alter nicotine extraction and effects. Dose-related changes were found in the magnitude and duration of action of measures such as reduction in urge to smoke and strength of effects observed. The second phase evaluated the relationship of the effects observed to plasma levels of nicotine; these were found to be closely related to the dose administered, thus confirming the reliability of this system of nicotine delivery. The study was smokeless cigarettes indicated similar dose-related effects as those found with the commercial tobacco products; nicotine levels were negligible, suggesting the possibility that this route of nicotine administration may produce effects mediated by its peripheral stimulus properties which resemble those of smoking cigarettes. Testing has been completed.